The reliability and sustainability of wireless, meshed, digital networks in underground mines has been severely limited by not only the lack of technology capable of existing in such terrain, but also by the ability to be effective in a post-event atmosphere (such as in areas after a hazmat incident, or other pollution or hazardous material explosions or spills, after military events, or in underground areas such as in a mine), and also by the lack of a commercially developed device that, as required by the Mine Safety and Health Administration (MSHA), is explosion proof or intrinsically safe.
“Intrinsically safe” generally means incapable of releasing enough electrical or thermal energy under normal or abnormal conditions to cause ignition of a flammable mixture of methane or natural gas and air of the most easily ignitable composition. (See 30 CFR Part 18) “Explosion-proof enclosure” generally means an enclosure that is so constructed that it will withstand internal explosions of methane-air mixtures: (1) Without damage to or excessive distortion of its walls or cover(s), and (2) without ignition of surrounding methane-air mixtures or discharge of flame from inside to outside the enclosure. (30 CFR Part 18) A WIFI or WIFI unit is an access point or router or phone or radio or any other client device which runs on about 802.11 b/g protocol which can interface via readers and gateways to other frequencies and protocols.
The West Virginia Mine Safety Technology Task Force was developed and tasked significantly in response to the Sago Mine Disaster of January 2006. The task force focused on needed improvements in the areas of equipment, capabilities, and processes for mine emergency response. (see Mine Safety Technology Task Force Report—May 29, 2006). There are many devices currently in use which are utilized to establish network connections when deployed in strategic locations within certain non-hazard or mining environments. However, the existing wireless Local Area Network (LAN) devices can not operate without limitation in the underground mining industry or in other post-traumatic event environments or hazardous situations and are not intrinsically safe. There are significant problems with meeting the MSHA requirement of intrinsic safety.
The tragic events at the Darby, Alma, and Sago coal mines have highlighted the need for reliable communications between miners inside and outside the mine. Current wire-based communications systems may fail due to exposure fires, roof falls or explosions tearing down wires, or triggering of power failure or battery failure. On Jun. 15, 2006 the “Miner Improvement and new Emergency Response Act of 2006” was signed by the President of the United States to amend the Federal Mine Safety and Health Act of 1977. As part of the Act underground coal mine operators must provide for post-accident communication between underground and surface personnel via a wireless two-way medium within the next three years. The Act also requires adoption of an electronic tracking system for surface personnel to determine the location of any person trapped underground. Robust and reliable mine communications are critical to this standard for both mining operations and in the event of a mine emergency.
Past mining accidents have demonstrated that current communication systems are not sufficient to provide the support required to effectively handle evacuation and rescue operations. Highly reliable voice and high speed data systems will enable mining operation dispatchers and rescue personnel to have enhanced situational awareness so that timely and correct actions can be taken. Reliable communication and data systems could thus provide significant cost savings by improving mining efficiency, allowing for early identification of hazardous conditions to avoid accidents, providing immediate communications of incidents to MSHA and dispatchers, and also providing assistance to mine rescuers in saving lives.